Diseases pose a significant threat to the health and survival of human race, which are the most important social issues for countries around the world. The advent and progress of stem cell transplantation have brought opportunity and hope to the patients who have been considered to be “incurable” by traditional treatment. While the sources of stem cells together with the safety and efficacy of transplantation therapy have always been the major scientific issues that the need to be addressed in cell based regenerative medicine
Hair follicle is one of the appendages of skin, originated in the interaction of epidermis and mesenchyme during embryonic development. In addition to keratinocyte stem cells and melonocyte stem cells, hair follicle also contains mesenchymal stem cells. The mesenchymal stem cells in hair follicle can not only self-renew, but also differentiate into bones, cartilage, fat and vascular smooth muscle and other tissue-specific cells. The self-renewal and differentiation of hair follicle stem cells have laid the cytological basis for the research and application of regenerative medicine of a variety of tissues and organs, including hair follicles. With advantages of easily accessible rich source of autologous stem cells, hair follicle stem cells exhibit the most clinical application potential over other adult stem cells currently known. However, the initiation of cell therapy needs large amount of highly proliferative stem cells, which can be achieved by repeated subculture of the anchorage dependent cells, such as hair follicle derived stem cells, in flasks or tissue culture petridishes. This process for harvesting of anchorage dependent cells not only reduce the proliferative capacity of the cells, but also deprive the cells of their potential to differentiate into a variety of tissue-specific cells, which may even induce the formation of tumor after transplant. As it is known that the amount of adherent cells harvested is proportional to culture area, namely: the larger the culture surface area is, the more amount of anchorage dependent cells harvest. Microcarrier has a high ratio of area to volume. The surface area of 1 kilogram of microcarriers with diameter of 100-300 microns, such as Cultisphere-G, is about 1 square meter. Thus with the use of microcarriers for cell culture surfaces, a large amount of adherent cells can be produced in a small amount of media, which can satisfy the number of cells required for cell based regeneration, avoid the reduction of cell proliferation capacity and the decline in differentiation potential as well as the risk of inducing tumor formation after transplantation, and also reduce the production costs. Therefore, the microcarrier cell culture system has been widely used in biological research and clinical application, and have achieved satisfactory results.